Distribution of glycogen in prefusion human palatal epithelium.

Various stages of embryonic human secondary palatal development were examined for the presence of epithelial glycogen. Utilizing periodic acid-Schiff's reagent staining of thick plastic sections and osmium ferrocyanide enhancement of thin sections, dramatic changes in epithelial glycogen distribution were noted during palatogenesis. Prior to fusion, the epithelium destined to adhere in the midline exhibited a marked diminution of glycogen in the superficial cell layer. This cell layer was composed of slender dense cells and cuboidal cells undergoing lysis. Adjacent nonfusing epithelium was markedly different and contained large glycogen reserves in its superficial cell layer. Glycogen may play a role either as precursor for specific adhesive macromolecules or as a physical agent capable under the influence of appropriate enzymes of causing cell lysis.